Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If cos(A + B) = 0 and sin(A - B) = 0, then what is the value of angle A and angle B ? (0 degree < A, B ≤ 90 degree).

Options:

20 degree, 70 degree

45 degree, 45 degree

15 degree, 75 degree

60 degree, 30 degree

Correct Answer:

45 degree, 45 degree

Explanation:

We are given :-

cos(A + B) = 0 and sin(A - B) = 0

So,  cos(A+B) = sin(A - B)

{ using concept :- Iff A + B = 90º  then sinA = cosB }

So, ( A + B ) + ( A - B ) = 90º

2A = 90º

A = 45º

And we know, cos ( A + B ) = 0  Iff ( A + B ) = 90º

So, 45º + B = 90º

B = 45º

Ans :-  A = 45º  and B = 45º